Azeotropic and pseudoazeotropic blends

ABSTRACT

The present invention relates to azeotropic blends and pseudoazeotropic blends and to coating compositions including such blends. In one aspect, an azeotropic blend or a pseudoazeotropic blend consists essentially of octamethyltrisiloxane and a second component selected from the following: amyl acetate, 2-propoxyethanol, 1-methoxy-2-propylacetate, and 1-propoxy-2-propanol.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/795,926, filed Jan. 23, 2019, which is incorporatedby reference herein in its entirety.

FIELD

The present invention relates to azeotropic blends or pseudoazeotropicblends that can be used, for example in coating compositions.

INTRODUCTION

Since the 1970s, paints and coatings formulators have struggled to meetvolatile organic compound (“VOC”) guidelines enacted by the UnitedStates Environmental Protection Agency (EPA) which have been gettingmore stringent in recent years. Among the approaches used by formulatorsto reduce the VOC content of their products is the replacement of VOCsolvents (e.g., toluene and xylene) with VOC-exempt solvents. Water is aVOC-exempt solvent used in waterborne coatings such as common houselatex paints. Acetone, t-butyl acetate, methyl acetate, andp-chlorobenzotrifluoride (PCBTF) are VOC-exempt solvents that are usedin solvent-based coatings. Other examples of VOC-exempt solvents arevolatile methyl siloxanes (“VMS”), which are relatively low molecularweight linear or cyclic compounds bearing fully methylated silicon atomsbridged by oxygen atoms.

Mixtures of liquids may exhibit “ideal” or “non-ideal” behaviordepending on the degree of association or interaction between thecomponents. In an ideal mixture, two liquids with different boilingpoints have little or no association, and as a result, the partialpressure exerted by each component over the solution at a giventemperature is proportional to their mole fractions in the solution, andthe total vapor pressure of this ideal solution is the sum of thepartial vapor pressures. This relationship is known as Raoult's law.Therefore, mixtures of the two components would have boiling pointsintermediate between the boiling points of the two pure components. Onthe other hand, the components of non-ideal mixtures display significantassociation resulting in deviations from Raoult's law. Positivedeviations result in mixture compositions that have boiling pointshigher than either of the pure components, and negative deviationsresult in mixture compositions that have boiling points lower thaneither of the pure components. Such mixtures are termed azeotropes andtheir compositions do not change with distillation. These mixturesevaporate with a constant composition, effectively behaving as a singlecomponent. This property makes them useful when trying to substitute agiven VOC solvent.

It would be desirable to have new azeotropes and pseudoazeotropes, andin particular, to have new azeotropes and pseudoazeotropes that canpotentially be used in paints and other coating compositions withreduced VOC content.

SUMMARY

The present invention provides azeotropes and pseudoazeotropes. In someembodiments, the azeotropes and pseudoazeotropes are binary mixtures. Insome aspects, the azeotropes and pseudoazeotropes can be used in paintsor other coating compositions and advantageously provide a reduced VOCcontent as compared to existing solvents.

In one aspect, the present invention provides an azeotropic blend or apseudoazeotropic blend consisting essentially of octamethyltrisiloxaneand a second component selected from the following: amyl acetate,2-propoxyethanol, 1-methoxy-2-propylacetate, and 1-propoxy-2-propanol.

In another aspect, the present invention provides a coating compositioncomprising any of the azeotropic blends or pseudoazeotropic blendsdisclosed herein.

These and other embodiments are described in more detail in the DetailedDescription.

DETAILED DESCRIPTION

As used herein, “a,” “an,” “the,” “at least one,” and “one or more” areused interchangeably.

The terms “comprising,” “including,” “having,” and their derivatives,are not intended to exclude the presence of any additional component,step or procedure, whether or not the same is specifically disclosed. Inorder to avoid any doubt, all compositions claimed through use of theterm “comprising” may include one or more additional compounds unlessstated to the contrary. In contrast, the term, “consisting essentiallyof” excludes from the scope of any succeeding recitation any othercomponent, step, or procedure, excepting those that are not essential tooperability. The term “consisting of” excludes any component, step, orprocedure not specifically delineated or listed. The term “or”, unlessstated otherwise, refers to the listed members individually as well asin any combination. Use of the singular includes use of the plural andvice versa.

Also herein, the recitations of numerical ranges by endpoints includeall numbers subsumed in that range (e.g., 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, 5, etc.). For the purposes of the invention, it is tobe understood, consistent with what one of ordinary skill in the artwould understand, that a numerical range is intended to include andsupport all possible subranges that are included in that range. Forexample, the range from 1 to 100 is intended to convey from 1.01 to 100,from 1 to 99.99, from 1.01 to 99.99, from 40 to 60, from 1 to 55, etc.

Unless stated to the contrary, implicit from the context, or customaryin the art, all parts and percents are based on weight and all testmethods are current as of the filing date of this disclosure.

“Azeotropic” and like terms mean a blend of two or more components thatboil or distill as a single component at a given temperature andpressure while the liquid and the vapor concentrations are the same.“Pseudo-azeotropic” and like terms mean a blend of two or morecomponents that boils or evaporates closely, but not exactly, like asingle component, i.e., the solvent system sufficiently approximates anazeotropic system so as to allow it to be used as an azeotropic system.Both azeotropic and pseudo-azeotropic blends have boiling points lowerthan either of the pure components used in the blend. Unless statedotherwise herein, the determination of whether a blend is azeotropic orpseudo-azeotropic is based on boiling points at 720 mm mercury (mm Hg).

“Solvent” and like terms mean a substance that is capable of dissolvinganother substance (i.e., a solute) to form an essentially uniformlydispersed mixture (i.e., solution) at the molecular or ionic size level.

“Hydrocarbon” and like terms mean a compound consisting only of carbonand hydrogen atoms.

“Solution” and like terms mean a homogeneous composition that is (1)variable, i.e., can exist in different concentrations of solute insolvent, (2) all but one component is present in simplest units, e.g.,molecules, and (3) can be separated by physical methods into two or morepure substances. In the context of this invention, solution refers toliquid compositions.

“Composition” and like terms mean a mixture or blend of two or morecomponents.

Embodiments of the present invention generally relate to azeotropicblends or pseudoazeotropic blends consisting essentially ofoctamethyltrisiloxane and a second component selected from thefollowing: amyl acetate, 2-propoxyethanol, 1-methoxy-2-propylacetate,and 1-propoxy-2-propanol.

In some embodiments, the azeotropic blend or pseudoazeotropic blendconsists essentially of octamethyltrisiloxane and amyl acetate. In someembodiments, the blend consists of octamethyltrisiloxane and amylacetate. The boiling point of the blend, in some embodiments, is lessthan the boiling point of octamethyltrisiloxane and less than theboiling point of amyl acetate at 720 mm Hg. In some such embodimentscomprising amyl acetate, the blend comprises 20 to 50 weight percentoctamethyltrisiloxane based on the total weight of the blend.

In some embodiments, the azeotropic blend or pseudoazeotropic blendconsists essentially of octamethyltrisiloxane and 2-propoxyethanol. Insome embodiments, the blend consists of octamethyltrisiloxane and2-propoxyethanol. The boiling point of the blend, in some embodiments,is less than the boiling point of octamethyltrisiloxane and less thanthe boiling point of 2-propoxyethanol at 720 mm Hg. In some suchembodiments comprising 2-propoxyethanol, the blend comprises 20 to 80weight percent octamethyltrisiloxane based on the total weight of theblend.

In some embodiments, the azeotropic blend or pseudoazeotropic blendconsists essentially of octamethyltrisiloxane and1-methoxy-2-propylacetate. In some embodiments, the blend consists ofoctamethyltrisiloxane and 1-methoxy-2-propylacetate. The boiling pointof the blend, in some embodiments, is less than the boiling point ofoctamethyltrisiloxane and less than the boiling point of1-methoxy-2-propylacetate at 720 mm Hg. In some such embodimentscomprising 1-methoxy-2-propylacetate, the blend comprises 20 weightpercent or less octamethyltrisiloxane based on the total weight of theblend.

In some embodiments, the azeotropic blend or pseudoazeotropic blendconsists essentially of octamethyltrisiloxane and 1-propoxy-2-propanol.In some embodiments, the blend consists of octamethyltrisiloxane and1-propoxy-2-propanol. The boiling point of the blend, in someembodiments, is less than the boiling point of octamethyltrisiloxane andless than the boiling point of 1-propoxy-2-propanol at 720 mm Hg. Insome such embodiments comprising 1-propoxy-2-propanol, the blendcomprises 20 to 50 weight percent octamethyltrisiloxane based on thetotal weight of the blend.

Embodiments of the present invention also relate to coatingcompositions. A coating composition of the present invention comprisesany of the azeotropic blends or pseudoazeotropic blends disclosedherein.

Blends

Blends according to embodiments of the present invention advantageouslybehave as azeotropes or pseudoazeotropes. The azeotropic blends andpseudoazeotropic blends of the present invention consist essentially of,or consist of, a first component and a second component. The firstcomponent is octamethyltrisiloxane. The second component is amylacetate, 2-propoxyethanol, 1-methoxy-2-propylacetate, or1-propoxy-2-propanol. The first and second components form the blend.The blend can be used as a solvent in some embodiments. Thus, someembodiments of the present invention relate to solvents that consistessentially of, or consist of, octamethyltrisiloxane and a secondcomponent selected from the following: amyl acetate, 2-propoxyethanol,1-methoxy-2-propylacetate, and 1-propoxy-2-propanol.

The first component in the blend is octamethyltrisiloxane.Octamethyltrisiloxane is commercially available from The Dow ChemicalCompany as XIAMETER™ PMX-200 silicone fluid, 1.0 cSt (centistokes). Asset forth further herein, the amount of octamethyltrisiloxane used inembodiments of the present invention depends on the second componentused (e.g., amyl acetate, 2-propoxyethanol, 1-methoxy-2-propylacetate,and 1-propoxy-2-propanol).

In some embodiments, the second component is amyl acetate. Amyl acetateis commercially available from The Dow Chemical Company and a variety ofother manufacturers. In some such embodiments, the blend or solventconsists essentially of octamethyltrisiloxane and amyl acetate. In somesuch embodiments, the blend or solvent consists of octamethyltrisiloxaneand amyl acetate. In embodiments where the second component is amylacetate, the blend comprises 20 to 50 weight percentoctamethyltrisiloxane based on the total weight of the blend. The blendor solvent, in some embodiments, consists essentially of 20 to 50 weightpercent octamethyltrisiloxane and 50 to 80 weight percent amyl acetate,based on the total weight of the blend. The blend or solvent, in someembodiments, consists of 20 to 50 weight percent octamethyltrisiloxaneand 50 to 80 weight percent amyl acetate, based on the total weight ofthe blend.

In some embodiments, the second component is 2-propoxyethanol.2-propoxyethanol is commercially available from The Dow Chemical Companyas Propyl CELLOSOLVE™. In some such embodiments, the blend or solventconsists essentially of octamethyltrisiloxane and 2-propoxyethanol. Insome such embodiments, the blend or solvent consists ofoctamethyltrisiloxane and 2-propoxyethanol. In embodiments where thesecond component is 2-propoxyethanol, the blend comprises 20 to 80weight percent octamethyltrisiloxane based on the total weight of theblend. The blend or solvent, in some embodiments, consists essentiallyof 20 to 80 weight percent octamethyltrisiloxane and 20 to 80 weightpercent 2-propoxyethanol, based on the total weight of the blend. Theblend or solvent, in some embodiments, consists of 20 to 80 weightpercent octamethyltrisiloxane and 20 to 80 weight percent2-propoxyethanol, based on the total weight of the blend.

In some embodiments, the second component is 1-methoxy-2-propylacetate.1-methoxy-2-propylacetate is commercially available from The DowChemical Company as DOWANOL™ PMA. In some such embodiments, the blend orsolvent consists essentially of octamethyltrisiloxane and1-methoxy-2-propylacetate. In some such embodiments, the blend orsolvent consists of octamethyltrisiloxane and 1-methoxy-2-propylacetate.In embodiments where the second component is 1-methoxy-2-propylacetate,the blend comprises 20 weight percent or less octamethyltrisiloxanebased on the total weight of the blend. The blend or solvent, in someembodiments, consists essentially of 20 weight percent or lessoctamethyltrisiloxane and 80 weight percent or greater1-methoxy-2-propylacetate, based on the total weight of the blend. Theblend or solvent, in some embodiments, consists of 20 weight percent orless octamethyltrisiloxane and 80 weight percent or greater1-methoxy-2-propylacetate, based on the total weight of the blend.

In some embodiments, the second component is 1-propoxy-2-propanol.1-propoxy-2-propanol is commercially available from The Dow ChemicalCompany as DOWANOL™ PnP. In some such embodiments, the blend or solventconsists essentially of octamethyltrisiloxane and 1-propoxy-2-propanol.In some such embodiments, the blend or solvent consists ofoctamethyltrisiloxane and 1-propoxy-2-propanol. In embodiments where thesecond component is 1-propoxy-2-propanol, the blend comprises 20 to 50weight percent octamethyltrisiloxane based on the total weight of theblend. The blend or solvent, in some embodiments, consists essentiallyof 20 to 50 weight percent octamethyltrisiloxane and 50 to 80 weightpercent 1-propoxy-2-propanol, based on the total weight of the blend.The blend or solvent, in some embodiments, consists of 20 to 50 weightpercent octamethyltrisiloxane and 50 to 80 weight percent1-propoxy-2-propanol, based on the total weight of the blend.

Blends or solvents according to embodiments of the present invention canbe prepared using techniques known to those of skill in the art based onthe teachings herein.

Coating Compositions

Some embodiments of the present invention relate to coatingcompositions. Coating compositions of the present invention comprise, invarious embodiments, any azeotropic blend or pseuodoazeotropic blenddisclosed herein. The azeotropic and pseudoazeotropic blends can besolvents in such coating compositions.

Examples of coating compositions that can incorporate an azeotropicblend or pseudoazeotropic blend of the present invention as a solventinclude, without limitation, paints (e.g., house paints, asphalt paints,industrial paints, etc.), paints used to coat metal, and other coatings.For example, the azeotropic and pseudoazeotropic blends can be used toreplace other solvents typically used in such coating compositions(e.g., paints) such as p-chlorobenzotrifluoride (PCBTF), n-butylacetate, methyl acetate, acetone, toluene, and others.

Persons of ordinary skill in the art can readily modify typical coatingcompositions to incorporate the inventive azeotropic or pseudoazeotropicblends as solvents based on the teachings herein. In addition tosolvent, typical coating compositions also include polymeric binders,pigments, and other additives. Examples of such coating compositions canbe found in W. Finzel, “Volatile Methylsiloxanes as Exempt Solvents inProtective Coatings”, J. of Coatings Technology, Vol. 68, No. 852, pp.69-72 (January 1996); US Patent Publication No. 2018/0148605; US PatentPublication No. 2014/0065432 and Product Bulletin from Reichhold forBeckosol 10-060.

Coating compositions of the present invention can be prepared usingtechniques known to those having ordinary skill in the art based on theteachings herein.

Some embodiments of the invention will now be described in detail in thefollowing Examples.

EXAMPLES

The following examples are given to illustrate the invention and shouldnot be construed as limiting its scope. All parts and percentages are byweight unless otherwise indicated.

A number of components are blended with octamethyltrisiloxane. Theoctamethyltrisiloxane used is XIAMETER™ PMX-200 silicone fluid, 1.0 cSt(centistokes) from the Dow Chemical Company. The components evaluated aspart of a binary blend with octamethyltrisiloxane are: amyl acetate(from The Dow Chemical Company), n-butyl propionate (UCAR™ n-ButylPropionate from The Dow Chemical Company), 2-propoxyethanol (PropylCELLUSOLVE™ from The Dow Chemical Company), 1-methoxy-2-propylacetate(DOWANOL™ PMA from The Dow Chemical Company), and 1-propoxy-2-propanol(DOWANOL™ PnP from The Dow Chemical Company).

Boiling Point Measurements

The boiling measurements of the pure components and the blends aremeasured as follows. In a typical experiment, 15 grams of the puresolvent or solvent blend to be tested is added to a single neck, 50 mLround bottom flask equipped with a built-in thermocouple well. A smallTeflon stir bar is added to the flask and the flask is secured on a ringstand with a clamp. A heating mantle is attached to the flask and amagnetic stir plate is placed beneath the mantle. Control and high limitthermocouples leading from a digital temperature controller are placedbetween the mantle and the flask. Another thermocouple is placed insidethe thermocouple well. A condenser is attached to the flask and anadapter leading to a nitrogen-vacuum line is placed on the condenser.The stir plate is turned on low speed. Dry ice is added to the vacuumtrap and the vacuum pump turned on. The pressure is adjusted to thedesired value by means of a Tescom backpressure regulator and nitrogenflow from a 5 psig nitrogen line. The pressure is read with a digitalRosemount gauge. The system had a relief valve in place so that overpressurization would not occur. The pressure in the apparatus isinitially reduced to about 10 mmHg and then increased to about 760 mmHgwith nitrogen. After this initial purging of air, the pressure is set to720 mm Hg. The temperature controller is turned on and the mantletemperature increased gradually in small increments until the liquid inthe flask is observed to boil and a reflux is established. Thetemperature of the boiling liquid measured at the thermocouple well isrecorded as the boiling point.

The boiling points of the neat XIAMETER™ PMX-200 fluid and of the neatsecond solvent (second component) of interest are measured beforemeasuring the boiling point of blends. Blends are made up with thefollowing weight percent compositions: 80/20 XIAMETER™ PMX-200 fluid(24.00±0.03 g) and second solvent (6.00±0.03 g); 50/50 XIAMETER™ PMX-200fluid (15.00±0.03 g) and second solvent (15.00±0.03 g); and 20/80XIAMETER™ PMX-200 fluid (6.00±0.03 g) and second solvent (24.00±0.03 g).Each blend made is labeled and stirred briefly to achieve solubility.For the boiling point determination, 15.00±0.03 g of blend was used.

The results are shown in Table 1.

TABLE 1 Boiling Point (° C) of Boiling Point XIAMETER ™ PMX-200 blend atof Second Given Weight % of XIAMETER ™ Second Component Component fluid(Second Solvent) (° C.) 100% 80% 50% 20% Amy Acetate 145 151.4 146 144*144* n-Butyl Propionate 143 151.4 147 144  144  2-propoxyethanol 150151.4  140* 140* 143* 1-methoxy-2- 135 151.4 143 135  129* propylacetate1-propoxy-2- 149 151.4 143 143* 145* propanolThe blends marked with an asterisk (*) represent inventive azeotropicblends according to some embodiments of the present invention.Solubility of Acrylic and Epoxy Resins in the Inventive AzeotropicBlends

To demonstrate the potential use of the inventive azeotropic blends incoating formulations, their compatibility with three common resins isevaluated at a theoretical concentration of 10% resin (weight of resinper volume of solvent, w/v). The resins used are: PARALOID™ B-66 100%acrylic resin (The Dow Chemical Company), PARALOID™ B-72 100% acrylicresin (The Dow Chemical Company), and DER® 331 epoxy resin (OlinCorporation). The resin (0.50±0.03 g) is weighed into a 16 mL vial, and5.0 ml of the specified azeotropic blend is pipetted into the vial,which is then capped with a polyethylene-lined lid and labeledappropriately. This procedure is repeated with each of the resins andthe azeotropic blends evaluated. The vials are placed in an Eberbachshaker on low setting. After 24 hours, the vials are removed from theshaker and allowed to sit on a lab bench for 30 minutes before they arevisually rated as soluble or insoluble. The ratings are summarized inTable 2.

TABLE 2 PARALOID ™ B-66 PARALOID ™ B-72 DER ™ 331 Azeotropic Composition(10% by wt.) (10% by wt.) (10% by wt.) 20% XIAMETER ™ PMX-200 SolubleSoluble Soluble 80% 1-methoxy-2-propylacetate 20% XIAMETER ™ PMX-200Soluble Soluble Soluble 80% 1-propoxy-2-propanol 50% XIAMETER ™ PMX-200Insoluble Insoluble Soluble 50% 1-propoxy-2-propanol 50% XIAMETER ™PMX-200 Insoluble Insoluble Soluble 50% 2-propoxyethanol 20% XIAMETER ™PMX-200 Soluble Soluble Soluble 80% 2-propoxyethanol 20% XIAMETER ™PMX-200 Soluble Soluble Soluble 80% amyl acetateAs shown above, depending on the specific blend and resin evaluated,resin solubility is observed in blends containing 20-50% of theoctamethyltrisiloxane. This demonstrated the potential use of low VOCazeotropic blends as solvents with common resins used in coatingcompositions.

We claim:
 1. An azeotropic blend or a pseudoazeotropic blend consistingessentially of octamethyltrisiloxane and a second component selectedfrom the following: amyl acetate at a percent by weight in a range of 50wt % to 80 wt %, 2-propoxyethanol at a percent by weight in a range of20 wt % to 80 wt %, 1-methoxy-2-propylacetate at a percent by weight of80 wt % or greater, and 1-propoxy-2-propanol at a percent by weight in arange of 50 wt % to 80 wt %; wherein the boiling point of the blend isless than the boiling point of both of octamethytrisiloxane and thesecond component.
 2. The blend of claim 1, wherein the second componentis amyl acetate.
 3. The blend of claim 1, wherein the second componentis 2-propoxyethanol.
 4. The blend of claim 1, wherein the secondcomponent is 1-methoxy-2-propylacetate.
 5. The blend of claim 1, whereinthe second component is 1-propoxy-2-propanol.
 6. A coating compositioncomprising the azeotropic blend or pseudoazetropic blend of claim 1.